Clicking a button on disconnected form should not fire submit event.

third_party/WebKit/Source/core/html/HTMLButtonElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp b/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
index e69bab33322cd66a0c1bd5355123fb1551df6561..6db54609990bca88c26588363ecf6653ae01254c 100644
--- a/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
@@ -105,6 +105,9 @@ void HTMLButtonElement::ParseAttribute(
 }
 
 void HTMLButtonElement::DefaultEventHandler(Event* event) {
+  if (!isConnected())

[tkent, 2017/05/23 06:55:26]

Here is not a right place to check this.
We have a similar issue with <input type=submit>.

HTMLFormElement::PrepareForSubmission() is the right place, I think.

[Shanmuga Pandi, 2017/05/23 10:34:04]

Done.

+    return;
+
   if (event->type() == EventTypeNames::DOMActivate &&
       !IsDisabledFormControl()) {
     if (Form() && type_ == SUBMIT) {